$$11x - 9 = -x^2 + 7x + (-5 + 2x^2)$$
$$11x - 9 = -x^2 + 7x - 5 + 2x^2$$
$$11x - 9 = x^2 + 7x - 5$$
$$x^2 + 7x - 11x - 5 + 9 = 0$$
$$x^2 - 4x + 4 = 0$$
$$(x - 2)^2 = 0$$
$$x - 2 = 0$$
$$x = 2$$
Ответ: 2